Chronic obstructive pulmonary disease (COPD) is one of the top lung diseases affecting the population and patients need expensive long term care. Emphysema and chronic bronchitis are two main categories of diseases that comprise COPD. Chronic bronchitis affects the small bronchioles of the airway tree in the lungs. The airways inside the lung exist in a tree like structure that can be best analyzed in three dimensions (3D).
The measurements of the airway wall and the lumen are the best indicators of the presence of bronchitis in the patients. In two-dimensions (2D) the normal airway cross sections are not always perpendicular to the cross section of the axial plane and this can produce erroneous results. One of the important measurements in the COPD is the determination of the wall thickness on the bronchial section. The airways of strong interest (in the 5th or below branch generations of the bronchial tree) are very small in size and with conventional imaging resolutions, an image of the airways of strong interest do not provide many voxels for analysis. Also the airways of strong interest are almost always accompanied by small blood vessels that can sometimes distort the analysis of the walls.